Improvement in projectiles for rifled cannon



JNO. M. SIGOURNEY, OF WATERTOWN, NEW YORK.

.IMPROVEMENT IN PROJECTILES FOR RIFLED CANNON.

Specification forming part of Leiters Patent No. 16,755, dated Marclr, 1857'.

T0 all whom it 171,04/ concern:

Be it known that I, JOHN M. SIGOURNEY, Of Watertown, in the county of Jefferson and State of New York, haveinvented certain new and useful Improvements in Shot and Shells.

for Riiied Ordnance; and I do hereby declare that the following is a true, full, and exact description thereof, reference being had to the accompanying drawings, in which" Figure l is an elevation of my improved shot or shell; Fig. 2, a cross-section through line y; Fig. 3, a section through yz of Fig. 2.

My invention relates to that form of cylindro-conical shot which has feathers or wings to give it the rotary motion on its axis; and it consists in so recessing the cylindrical part of the shot between the feathers or guides that the feathers may be planed to fit the grooves, and the annular projections or flanges left by such recessing may be turned off to fit the bore of the gun with accuracy.

In ritled ordnance it is of the first importance to haveythe projectile fit the bore of the .gun very accurately. This I secure by castvallows^ the manner of finishing described. 4'Ihatpartof the ball between the belts is of a diameter sufficiently less than that of the bore of the gun, so that it does not come in contact with it, and is not finished. When the gun is rifled, the grooves are accurately spaced, as are the ribs in theball. The latter are planed by a machine purposely, made, which gives them the same spiral or twist as the grooves,

thus making a male and female screw. By this shape I secure a constant diameter to the ball, and the minimum of windage and the surfaces in friction are finished so that the Wear is greatly reduced. This construction1 insures the rotary motion to the projectile, and the continuance of the said motion depends mostly upon the degree of twist given to the grooves in the gun. If this is sufficient, the rotary motion will be kept up through the whole course of its flight. c The shot is of the usual cylindro-conical form, and may assume the various modifications in the shape of the points or ribs, and may also vary as to quantity of ribs, &c. Shells are made of the same exterior form, with a percussion arrangement communicating with the powder in the cavity of the shell to explode it on striking the. object aimed at. In manufacturing these projectiles they are cast with the concavity downward, in order that the metal may be balanced around its vertical aXis. j

Having now fully described my improvement, what I claim as my invention, and desire to secure by Letters Patent, is-

Recessing the cylindrical part of cylindroconical shot and shells in such a mann'er that the contact of said shot and shells with the bore and grooves of thegun be confined to the projecting ribs B and belts A, which belts and ribs are nished to fit the bore and grooves with precision, substantially as set forth.

In testimony whereof I have signed my name to this specification before two subscribing witnesses.

J N O. M. SIGOURNEY. Witnesses:

A. PoLLAK, JOHN WHIPPLE. 

